Many military vehicles, such as aircraft, for example, are powered by gas turbine engines wherein each of such engines emits infrared radiation from hot metal parts thereof and from its exhaust gas plume making the associated vehicle particularly vulnerable to missiles which seek and home on such infrared radiation in an effort to destroy the vehicle.
Because of deficiencies of many of the previously proposed infrared radiation suppressors and as outlined in U.S. Pat. No. 4,007,587, it was proposed in this patent to provide an apparatus for and method of suppressing infrared radiation which utilizes fixed though adjustable components in a duct structure which is basically a one-part structure. However, the one-part structure disclosed by this patent is difficult to mount or install in a vehicle, requires additional vibration isolation bellows and flanges resulting in added weight, and does not provide maximum film cooling of metal surfaces of the apparatus.
It has also been proposed in U.S. Pat. No. 4,018,046 to provide an apparatus for and method of suppressing infrared radiation employing two separate main parts defined by an ejector vane assembly having radially disposed vanes and a dogleg duct wherein cooling ambient air is also introduced through an annular passage between the vane assembly and dogleg duct. However, the apparatus and method of this latter patent do not provide mixing of one or more streams of cooling ambient air with hot engine exhaust gases such that the hot gas stream is effectively split across its full dimension so as to produce a highly efficient mixing of cooling ambient air with hot exhaust gases and a cooler exhaust gas plume; and do not provide maximum air film cooling of metal parts.
Accordingly, it is a desired objective to provide an apparatus for and method of suppressing infrared radiation emitted from hot metal parts at the aft end of a gas turbine engine and from the exhaust gas plume thereof which utilizes an assembly of a plurality of fixed cooperating component parts wherein the assembly provides a substantial amount of cooling ambient air with maximum air film cooling of metal parts of such assembly and maximum dilution of the exhaust gas plume for a minimum infrared signal.